Re: [Qemu-devel] [PATCH v8 2/4] vfio: Add vfio_container_ioctl()

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 06/07/2014 02:48 AM, Alex Williamson wrote:
> On Fri, 2014-06-06 at 13:34 +1000, Alexey Kardashevskiy wrote:
>> While most operations with VFIO IOMMU driver are generic and used inside
>> vfio.c, there are still some operations which only specific VFIO IOMMU
>> drivers implement. The first example of it will be reading a DMA window
>> start from the host.
>>
>> This adds a helper which passes an ioctl request to the container's fd.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>> Changes:
>> v8:
>> * s/vfio_container_spapr_get_info/vfio_container_ioctl/ - now it is
>> generalized
>>
>> v7:
>> * do not return a group fd from the helper
>>
>> v6:
>> * added dup() to protect group_fd from accidental disposal
>>
>> v5:
>> * reworked to reflect change in vfio_get_group() from one
>> of previous patches change
>>
>> v4:
>> * fixed possible leaks on error paths
>> ---
>>  hw/misc/vfio.c         | 28 ++++++++++++++++++++++++++++
>>  include/hw/misc/vfio.h |  9 +++++++++
>>  2 files changed, 37 insertions(+)
>>  create mode 100644 include/hw/misc/vfio.h
>>
>> diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
>> index 7437c2e..bb77934 100644
>> --- a/hw/misc/vfio.c
>> +++ b/hw/misc/vfio.c
>> @@ -39,6 +39,7 @@
>>  #include "qemu/range.h"
>>  #include "sysemu/kvm.h"
>>  #include "sysemu/sysemu.h"
>> +#include "hw/misc/vfio.h"
>>  
>>  /* #define DEBUG_VFIO */
>>  #ifdef DEBUG_VFIO
>> @@ -4318,3 +4319,30 @@ static void register_vfio_pci_dev_type(void)
>>  }
>>  
>>  type_init(register_vfio_pci_dev_type)
>> +
>> +int vfio_container_ioctl(AddressSpace *as, int32_t groupid,
>> +                         int req, void *param)
>> +{
>> +    VFIOGroup *group;
>> +    VFIOContainer *container;
>> +    int ret = -1;
>> +
>> +    group = vfio_get_group(groupid, as);
>> +    if (!group) {
>> +        error_report("vfio: group %d not registered", groupid);
>> +        return ret;
>> +    }
> 
> Gavin's version of this walked existing groups and returned an error if
> not found.  vfio_get_group() will go out and create a group and connect
> it to a container.  I'm not sure we really want to expose that sort of
> capability out to the reset of QEMU.  Thanks,


If it is not created here, then it can only be created from vfio_initfn()
which is too late as I need group to get DMA window properties for PHB when
PHB is being realized.

Add another helper?


> 
> Alex
> 
>> +
>> +    container = group->container;
>> +    if (group->container) {
>> +        ret = ioctl(container->fd, req, param);
>> +        if (ret < 0) {
>> +            error_report("vfio: failed to ioctl container: ret=%d, %s",
>> +                         ret, strerror(errno));
>> +        }
>> +    }
>> +
>> +    vfio_put_group(group);
>> +
>> +    return ret;
>> +}
>> diff --git a/include/hw/misc/vfio.h b/include/hw/misc/vfio.h
>> new file mode 100644
>> index 0000000..0b26cd8
>> --- /dev/null
>> +++ b/include/hw/misc/vfio.h
>> @@ -0,0 +1,9 @@
>> +#ifndef VFIO_API_H
>> +#define VFIO_API_H
>> +
>> +#include "qemu/typedefs.h"
>> +
>> +extern int vfio_container_ioctl(AddressSpace *as, int32_t groupid,
>> +                                int req, void *param);
>> +
>> +#endif
> 
> 
> 


-- 
Alexey